Tooth whitening product

ABSTRACT

A tooth whitening product is provided. The tooth whitening product has a backing layer and a tooth whitening composition. The tooth whitening composition includes first and second water soluble polymers, water, and a tooth whitening agent, wherein the first water soluble polymer is polyethelene oxide and the second water soluble polymer is polyvinyl alcohol.

FIELD OF THE INVENTION

The present invention relates to products for whitening teeth, and, moreparticularly, to products for whitening teeth that have a whiteningagent incorporated therein.

BACKGROUND OF THE INVENTION

Tooth whitening has become very popular over the past few years. Moreand more consumers are choosing to whiten their teeth. Options for toothwhitening include toothpastes, mouthrinses, chewing gums, in-officebleaching, and most commonly tooth whitening solutions used with a trayobtained either over-the-counter or from a dentist. Tooth whiteningproducts using a strip of material in combination with a chemicalwhitening active are known in the art. For example, U.S. Pat. No.6,419,906, the substance of which is incorporated herein by reference,describes a tooth whitening product comprising a strip of materialformed from a water hydratable polymer and a tooth whitening agent.While these whitening products may function for their intended purpose,there is continuing desire to improve the handling and aesthetics ofthese tooth whitening products.

SUMMARY OF THE INVENTION

A tooth whitening product is provided. The tooth whitening product has abacking layer and a tooth whitening composition. The tooth whiteningcomposition includes first and second water soluble polymers, water, anda tooth whitening agent, wherein the first water soluble polymer ispolyethelene oxide and the second water soluble polymer is polyvinylalcohol.

BRIEF DESCRIPTION OF THE DRAWINGS

While the specification concludes with claims particularly pointing outand distinctly claiming the invention, it is believed that the presentinvention will be better understood from the following description takenin conjunction with the accompanying drawings in which:

FIG. 1 is a cross-sectional side view of tooth whitening product made inaccordance with the present invention, wherein a coating of a toothwhitening agent has been applied to a film;

FIG. 2 is a perspective view of another embodiment of a tooth whiteningproduct of the present invention, wherein the tooth whitening productcomprises a web and a coating that completely bridges the void spaces ofthe web and wherein a portion of the coating has been removed to revealfeatures there below;

FIG. 3 is a cross-sectional side view of the tooth whitening product ofFIG. 2, wherein the void spaces are shown as partially filled;

FIG. 4 is a cross-sectional side view of the tooth whitening product ofFIG. 2, wherein the void spaces are shown as completely filled;

FIG. 5 is a perspective view of another embodiment of a tooth whiteningproduct of the present invention, wherein the tooth whitening productcomprises a web and a coating that partially bridges the void spaces ofthe web;

FIG. 6 is a perspective view of another embodiment of a tooth whiteningproduct of the present invention, wherein the tooth whitening productcomprises a web and a coating that does not bridge the void spaces ofthe web;

FIG. 7 is a cross-sectional side view of another embodiment of a toothwhitening product of the present invention that comprises a perforatedfilm; and

FIG. 8 is a perspective view of another embodiment of a tooth whiteningproduct of the present invention that comprises a first layer and asecond layer.

DETAILED DESCRIPTION OF THE INVENTION

All weight percentages herein refer to the tooth whitening compositionafter processing (e.g., after drying, cooling, curing, extrusion, orcasting). Reference will now be made in detail to embodiments of theinvention, examples of which are illustrated in the accompanyingdrawings wherein like numerals indicate the same elements throughout theviews and wherein elements having the same two last digits (e.g., 20 and120) connote similar elements. The present invention is directed totooth whitening products comprising a tooth whitening compositionincluding a tooth whitening or bleaching agent and one or more watersoluble polymers and, optionally, water, and a plasticizer. In anotherembodiment, the invention is directed to a tooth bleaching compositioncomprising a tooth whitening agent and a polyethylene oxide polymer anda polyvinyl alcohol polymer. As used herein, the phrase “water soluble”preferably means a compound or composition whose solubility in water isgreater than 5 wt %, preferably greater than 10 wt %, or more preferablygreater than 15 wt % when measured in water at 20 C without the aid ofpH adjusting agents, including solutes which are require temperaturesgreater than 20 C to solubilize in water but which still have theabove-stated weight percentages when the solution is cooled to 20 C.Solubility is determined by More preferably, “water soluble” means acompound or composition whose solubility in water is greater than 5 wt%, preferably greater than 10 wt %, or more preferably greater than 15wt % when first mixed in water at 20 C without the aid of pH adjustingagents. The water soluble polymers are also preferably water hydratable.As used herein, the phrase “water hydratable” is intended to refer to acompound or composition that absorbs water. While the present inventionwill be described herein with respect to these films or strips, it iscontemplated that the present invention can be used with other toothwhitening products, such as dental trays. Water soluble polymers, whichare also water hydratable, suitable for use with the present inventioninclude ethylene oxide polymers, homopolymers or mixtures of ethyleneoxide polymers of varying molecular weight ranging from about 10,000Daltons and up to about 10,000,000 Daltons and preferably in the rangeof about 100,000 to about 1,500,000 Daltons. Such ethylene oxidepolymers are commercially available from various sources. Polyethyleneoxide in the molecular weight range of 10,000 to 1,000,000 Daltons isavailable from the Union Carbide Company under the tradename “Polyox”.Other suitable polymers include polypropylene oxide, cross-linkedpolyacrylic acid, e.g., Carbopol, linear polyacrylic acid, polyvinylalcohol, sodium alginate, methyl methacrylate, xanthan gum, pectin,pullulan, guar gum, agar, polyvinyl pyrolidone (PVP), carrageanan,celluloses (e.g., hydroxypropylcellulose, hydroxyethyl cellulose,hydroxypropylmethyl cellulose and hydroxymethyl cellulose), polyethyleneoxide polypropylene oxide copolymers (e.g., poloxamer), microcrystallinecellulose, polyvinyl pyrolidone polyvinyl acetate copolymers, poly vinylester-methyl_copolymers, polyoxyethelene-polyoxypropylene blockcopolymer, and mixtures thereof. While the thickness of the film mayvary, as described more fully hereafter, the film may have a thicknessbetween about 0.1 micrometer and about 1500 micrometer (μm). The toothwhitening composition may be provided as a standalone film or may beapplied to, coated on, or otherwise provided with a backing layer orstrip of material. The backing layer can be provided as a single layeror as a laminate formed from a plurality of layers, such as anycombination of a foam, mesh, or a strip of material. The backing layercan be water permeable, water impermeable, or partially water permeable.The backing layer can be continuous or discontinuous (i.e., formed froma plurality of discrete segments). Examples of some suitable backinglayers are described in U.S. Pat. Nos. 5,891,453; 5,989,569; and2004/0005277.

Hydration of the water soluble polymer by saliva in the oral cavityallows release (e.g., solubilizes, diffuses, or mobilizes) of thewhitening agent incorporated in the polymer matrix. The whitening agentreleases from the tooth whitening product to the tooth surfaces to whichthe tooth whitening composition is applied. Whitening or bleachingagents suitable for the practice of the present invention includeperoxides, metal chlorites, perborates, percarbonates, peroxyacids,persulfates, and combinations thereof. Suitable peroxide compoundsinclude hydrogen peroxide, urea peroxide, calcium peroxide, and mixturesthereof. Suitable metal chlorites include calcium chlorite, bariumchlorite, magnesium chlorite, lithium chlorite, sodium chlorite, andpotassium chlorite. The preferred chlorite is sodium chlorite. Apreferred percarbonate is sodium percarbonate. Preferred persulfates areoxones.

Optionally, the water soluble polymer may be mixed with a plasticizer.Suitable plasticizers include glycols such as propylene glycol,polyethylene glycol, methoxypolyethylene glycol, polyhydric alcoholssuch as glycerin sorbitol, and xylitol, and glycerol esters such asglycerol triacetate. Glycerin can be used as well as propylene glycol orpolyethylene glycol such as is available from Union Carbide Corporationas their series of Carbowaxes that range in molecular weight from 200 to600 Daltons. Other plasticizers include cellulose esters, sebacateesters, castor oil, tricresyl phosphate, phthalate, adipate, ethylcitrate, ethanolamine, and oligosaccharides.

Optionally, any of the tooth whitening compositions described herein mayfurther include an amount of water. The amount of water that is presentmay be varied by the amount of drying or curing that occurs. Theembodiments of the present may include greater than about 2%, or about4%, or about 6% or about 10% and/or less than about 90%, or about 40%,or about 30% of water by weight percent of the tooth whiteningcomposition after drying.

In one embodiment of the present invention, a tooth whitening product 20comprises a water soluble polymeric film 22 and a solid whitening agentthat has been applied as a coating 24 to one side of the water solublepolymeric film 22, as shown in FIG. 1. The solid tooth whitening agentcan be applied while the film is still tacky or after the film hasdried, cured, or cooled. Application of the tooth whitening agent inthis manner reduces exposure of the tooth whitening agent to any waterthat may have been used as a solvent in forming the film and alsoreduces the amount of contact between the water soluble polymer and thetooth whitening agent in comparison to a water hydratable film having atooth whitening agent dispersed there throughout. In addition, thisembodiment has an increased concentration of the tooth whitening agentat the surface that is applied to the teeth. Such a coating can alsoassist in the diffusion of the tooth whitening agent toward the toothsurface since the coating is directly adjacent and/or in contact withthe tooth surface during use. Suitable solid tooth whitening agents thatcan be applied to one side of a water soluble polymeric film includecarbimide peroxide, calcium peroxide, percarbonate, sodium percarbonate,perborates, persulfates, and mixtures thereof. These tooth whiteningagents can be sprayed, applied by gravure printing, mist grinding, droppowdering, and other processes known in the art.

The coating of the solid tooth whitening agent can cover all or aportion of the water soluble polymeric film. The thickness of thecoating can be greater than about 0.001 microns, or greater than about0.005 microns, or greater than about 0.01 microns or greater than about0.05 microns, or greater than about 0.1 microns, or greater than about 1micron, or greater than 5 microns and/or less than about 100 microns, orless than about 50 microns, or less than about 10 microns, or less thanabout 1 micron. The dose per unit area of the tooth whitening agent isat least about 0.001 mg/cm², or at least about 0.005 mg/cm², or at leastabout 0.01 mg/cm², or at least about 0.05 mg/cm², or at least about 0.1mg/cm², or at least about 1 mg/cm², or at least about 10 mg/cm², or atleast about 100 mg/cm² and/or less than about 500 mg/cm², or less thanabout 250 mg/cm², or less than about 100 mg/cm², or less than about 10mg/cm². Other materials can be mixed with the solid tooth whiteningagent or applied sequentially before or after application of the solidtooth whitening agent. For example, binders, adherents, starches,sweeteners and flavorants, colorants (e.g., to aid in distinguishing theactive side of the strip from the non-active side), release agents(e.g., talc powder, manitol powder, lecithin, corn oil, bees wax,silica, calcium monostearate, glycerol monostearate, alkali salts oflong chain fatty acids) which facilitate release of the tooth whiteningcomposition from a surface such as a casting plate, pH adjusting agents,including alkalizing agents or acidifying agents, surfactants (e.g.,polysorbate 80 and glyceryl oleate), and other oral care actives can beapplied as part of the application step. While the solid tooth whiteningagent can be applied in a dry form, it is contemplated that a solventcould be used with the tooth whitening agent during application. In oneembodiment, a solvent that solubilizes both the water soluble polymerand the tooth whitening agent can be employed when applying the toothwhitening agent to the surface of the water soluble film. In thisprocess, the tooth whitening is solubilized in the solvent and thenapplied to the surface of the water soluble film so that the toothwhitening agent is dispersed at least partly within the film as thesolvent can solubilize a portion of the film. Alternatively, the solventmay only solublize the tooth whitening agent, in which case a discretecoating would be formed on one side of the film after solventevaporation or removal. Suitable solvents could include solvents thatcan solubilize the tooth whitening agent at a given temperature butwhich do not solubilize the water soluble polymer at that temperature.Some examples include Cellosolve acetate, anisole, 1,4 dioxane, ethylacetate, ethylenediamine, dimethyl Cellosolve, Cellosolve solvent,alcohols such as ethanol, methanol, or iso-propanol, Carbitol solvent,n-butanol, cuyl Cellosolve, n-butyl acetate, 2-propanol, and methylCellosolve, and mixtures thereof.

The water soluble polymeric film 22 can be prepared using a conventionalextrusion, calendaring, pressing or solvent casting processes. Forexample, to prepare a film by solvent casting polyethylene oxide, theethylene oxide polymer or mixture of polymers is dissolved in asufficient amount of a solvent which is compatible with the polymer.Examples of suitable solvents include water, alcohols, acetone, ethylacetate or mixtures thereof. After a solution has been formed, aplasticizer is added with stirring, and heat is applied if necessary toaid dissolution, until a clear and homogeneous solution has been formed,followed by the addition of the whitening agent and any otheringredients such as flavors. The solution is coated onto a suitablecarrier material and dried to form a film. The carrier material musthave a surface properties that allow the polymer solution to spreadevenly across the intended carrier width without soaking in to form adestructive bond between the two substrates. Examples of suitablecarrier materials include glass, stainless steel, teflon,polyethylene-impregnated kraft paper. The solution can also be cast ontothe previously described backing layers, a pouch or a portion of apackage for the tooth whitening composition. Drying of the film may becarried out in a high-temperature air-bath using a drying oven, dryingtunnel, vacuum drier, or any other suitable drying equipment, afterwhich the tooth whitening agent can be sprayed onto the film.

In another embodiment of the present invention, the efficacy and/orstability of the tooth whitening agent can be increased by forming thewater soluble film with a solvent other than water so that the toothwhitening agent does not come into contact with water during theformation process and there is no residual water left in the film postmanufacture. As used herein, the term “stability” is intended to referto the propensity of a material to maintain its original concentrationor structure over a fixed period of time. As used herein, the term“efficacy” is intended to refer to the amount of tooth whitening perunit time. In one process, the water soluble polymer and the toothwhitening agent are mixed and then fed to an extruder whose screw,through mechanical action, melts the water-hydatratable polymer. Themelted polymer is then extruded into a film to be formed into the toothwhitening product.

The efficacy of the tooth whitening agent can also be increased byreducing the amount of water soluble polymer that forms the film. In oneembodiment, the water soluble polymer film further comprises waterinsoluble organic and/or inorganic additives to reduce the amount of thewater soluble polymer so that solubilization of the tooth whiteningagent is maximized during use. Suitable water insoluble organicmaterials include polyolefins (e.g., polyethylene, polypropylene,polybutenes, polyisoprenes, and copolymers thereof) and polyester.Suitable water insoluble inorganic materials include calcium phosphate,calcium pyrophosphate, and titanium dioxide, and silica. The waterinsoluble additives can comprise at least about 10%, or at least about20%, or at least about 30% and/or less than about 90%, or less thanabout 80%, or less than about 70%, or less than about 50% or less thanabout 40%, or less than about 30% by weight of the film. In theseembodiments, the amount of the water soluble polymer is at least about5%, or at least about 10%, or at least about 20%, or at least about 30%and/or less than about 90%, or less than about 80%, or less than about70% by weight of the film. The water insoluble additives can be groundprior to incorporation into the film. In one embodiment, the averageparticle size of the water insoluble additives is at least about 1micron, or at least about 20 microns, or at least about 25 micronsand/or less than about 100 microns, or less than about 50 microns, orless than about 25 microns, or less than about 10 microns. In additionto decreasing the amount of water soluble polymer that is available toreact with the tooth whitening agent, the concentration of toothwhitening agent available at the surface of the tooth can be increasedduring hydration, because more water is available to solubilize thetooth whitening agent rather than hydrating or otherwise solubilizingthe water soluble polymer. The tooth whitening agent can be admixed withthe water soluble polymer as described in U.S. Pat. No. 6,419,906 orcoated onto the film as previously described.

In yet another embodiment of the present invention, a web, scrim, ormesh is incorporated in the tooth whitening product to improve thehydration of the film. The web, scrim, or mesh can be formed from fibersthat are aligned in random or repeating geometric patterns. Referring toFIG. 2, a tooth whitening product 120 comprising a web 32 isillustrated. The web 32 is formed from fibers 34 that are arranged in arepeating geometric pattern. The fibers can be formed from one or morewater insoluble, water soluble, or water hydratable polymers and mayhave a tooth whitening agent incorporated therein. If the fibers areformed from water insoluble materials, the web may function in a mannersimilar to the previously described films that incorporate waterinsoluble materials. The fibers are arranged in a manner to provide voidspaces 36 between the fibers. The void spaces can facilitate hydrationof the web 32 and therefore solubilization of the tooth whitening agent.The void spaces can vary in size or have a substantially constant sizeover the web. For example, the void spaces might be smaller in oneregion and larger in another region depending upon the desired rate ofhydration. The fibers 34 can have a diameter of at least about 1 micron,or at least about 5 microns, or at least about 10 microns, or at leastabout 20 microns, or at least about 50 microns and/or less than about200 microns, or less than about 100 microns, or less than about 50microns, or less than about 20 microns. The spacing 38 between fibers isat least about 1 micron, or at least about 5 microns, or at least about10 microns, or at least about 20 microns, or at least about 50 microns,or at least about 1 mm, or at least about 1.5 mm and/or less than about5 mm, or less than about 2.5 mm, or less than about 1.5 mm, or less thanabout 50 microns.

In an alternate embodiment, a tooth whitening product 220, shown in FIG.3, comprises a web 32 having a coating or layer 44 applied thereto. Theweb 32 can be formed a water soluble, water insoluble, or waterhydratable polymer or other material, such as other polymers (e.g.,polypropylene, polyethylene, etc.) and cellulose. The fibers 34 of theweb 32 can be arranged in a random or repeating pattern. The coating 44comprises a water soluble polymer and a tooth whitening agent. Othermaterials can be included in the coating, such as a plasticizer, water,water insoluble additives, etc. The coating can bridge the void spaces36 such that a substantially solid layer is formed on web 32. Thecoating might completely fill the void spaces as shown in FIG. 3 orpartially fill the void spaces as shown in FIG. 4 with respect to toothwhitening product 320. When the void spaces are partially filled, thepocket 50 that is formed can facilitate hydration of the web andtherefore solubilization and release of the tooth whitening agent.Alternatively, the coating 44 can only partially bridge the void spaces,as shown in FIG. 5 for the tooth whitening product 420. In yet anotherembodiment, a coating 44 does not bridge the void spaces 36 of web 32but merely coats the fibers 34, either wholly or partially, as shown byway of example in FIG. 6 for the tooth whitening product 520.

The concentration of the tooth whitening agent within the coating and/orthe fibers and the amount of water soluble polymer can be varied withinthese web embodiments depending upon the extent to which the coatingbridges the void spaces and/or coats the fibers and based upon thedesired rate of solibilization of the tooth whitening agent. As will beappreciated, any combination of completely filling the voids, partiallyfilling the voids, partially bridging the voids, and coating the fiberscan be provided in one embodiment.

In a related embodiment, a perforated film without a distinct web orscrim might be provided, as shown in FIG. 7. In the tooth whiteningproduct 620, a single or multilayer film might be provided comprising awater soluble polymer, a tooth whitening agent, a plasticizer, andoptionally water. The film can be perforated after it has dried orcured. The void spaces, holes, or apertures 630 that are formed duringthe perforation process can pass completely through the thickness of thefilm or might only partially penetrate the film thickness. The voidspaces 636 can have the same dimensions as previously described withrespect the void spaces of the web. The void spaces 636 can be providedin a random or repeating pattern and vary in size and shape aspreviously described. Further, this embodiment can include a coating ofa tooth whitening agent as previously described or other features of theembodiments discussed above.

In another embodiment of the present invention, a tooth whiteningproduct 720 is provided in the form of a laminated film as shown in FIG.8. The laminated film comprises two or more layers comprising waterhydratable polymers. A first layer 64, which is to be applied to theteeth, further comprises a tooth whitening agent. The water hydratablepolymer comprises at least about 1%, or at least about 10%, or at leastabout 20% and/or less than about 90%, or less than about 70%, or lessthan about 50% by weight of the first layer. The tooth whitening agentcomprises at least about 1%, or at least about 10%, or at least about15% and/or less than about 70%, or less than about 60%, or less thanabout 50% by weight of the first layer. The balance of the first layercan comprise water or other materials, such as the previously describedwater insoluble additives or a plasticizer. The second layer 66, whichis positioned adjacent the lips and/or cheeks during use, preferablydoes not comprise a tooth whitening agent. The water hydratable polymerof the second layer 66 comprises at least about 20%, or at least about30%, or at least about 40% and/or less than about 100%, or less thanabout 90%, or less than about 80% by weight of the second layer. Aplasticizer comprises at least about 0.1%, or at least about 1%, or atleast about 2% and/or less than about 40%, or less than about 30%, orless than about 20% by weight of the second layer. The balance of thesecond layer 66 can comprise other materials, such as water, waterinsoluble additives, or oral care actives other than a tooth whiteningagent. Examples of other oral care actives suitable for use with thepresent invention include phosphates (e.g., pyrophosphates,polyphosphate, polyphosphonates, and mixtures thereof), fluoride ionsources, antimicrobial agent, anti-imflamatory agents, nutrients, andenzymes. These oral care actives are further described in U.S. Pat. No.6,096,328 (and the patents cited therein), the substances of which areincorporated herein by reference. These other oral care actives couldalso be incorporated into a film comprising only a single layer andformed from a water-hydratable polymer (e.g., polyethyylene oxide) and aplasticizer, the basic formation of which is described in U.S. Pat. No.6,419,906.

The composition of the first layer 64 and the second layer 66 of thetooth whitening product 720 can be adapted to provide differentfunctionalities. For example, the first layer 64 might comprise less ofthe water hydratable polymer than the second layer 66 so that the firstlayer 64 hydrates more quickly thereby solubilizing the tooth whiteningagent more quickly and more effectively (i.e., providing a greaterconcentration more quickly). The second layer can contain relativelymore of the water hydratable polymer so that it functions as a barrierlayer preventing diffusion of the solubilized tooth whitening agent awayfrom a tooth while still permitting some hydration from the back side ofthe tooth whitening product. Also, since the second outer layercomprises more of the water soluble polymer, it will remain in afilm-like state longer than the first layer 64 so that the toothwhitening agent will have a longer period of time in which to act uponthe teeth. The absence of the tooth whitening agent from the secondlayer could also improve tissue tolerablity as a peroxide source wouldnot be directly adjacent the soft tissue of the lips and cheeks. Thetooth whitening product 720 can be formed by casting the first layerfirst followed by the second layer being cast on top of the first layereither before or after the first layer has dried or cured. The layerscan be pressed together by rollers aligned so that there is nip of gapthere between through which the first and second layers pass. The firstand second layers can comprise the same water soluble polymer ordistinct water soluble polymers.

In another aspect of the present invention, a film comprising a watersoluble polymer and a tooth whitening agent is provided in a thin formand with an increased concentration of the tooth whitening agent. Thethickness of the film is at least about 1 μm, or at least about 5 μm, orat least about 10 μm, or least about 15 μm and/or less than about 2 mm,or less than about 1 mm, or less than about 0.5 mm, or less than about0.25 mm, or less than about 0.1 mm, or less than about 20 μm, or lessthan about 15 μm. The concentration of the tooth whitening agent is atleast about 1%, or at least about 10% or at least about 15%, or at leastabout 20%, or least about 25% and/or less than about 70%, or less thanabout 60%, or less than about 50%, or less than about 40%, or less thanabout 30%. Surprisingly, these increased concentration levels of thetooth whitening agent can be utilized while still maintaining acceptablesoft tissue tolerability without the need for cumbersome rubber dams orother artificial soft tissue barriers. As used herein, the phrase“artificial barrier” is intended to refer to any physical means thatprevents or is intended to prevent a tooth whitening agent frommigrating onto the soft tissue adjacent the teeth during a bleachingoperation. Other artificial barriers can include light cured resins. Asused herein, the phrase “soft tissue tolerability” is intended to referto the degree to which a user experiences a sensation often described asburning or stinging or experiences irritation of the gingival tissues.This sensation can range from minor to severe. In addition, one or morelayers, preferably without a tooth whitening agent, can be providedadjacent the previously described layer containing the tooth whiteningagent.

In another embodiment, the tooth whitening composition comprises two ormore water soluble polymers, a tooth whitening agent, and optionally aplasticizer, and/or water. The tooth whitening composition may beprovided as a layer on a backing layer, as as a stand-alone film, or inother forms. In a preferred embodiment, the first water soluble polymeris a polyethylene oxide polymer and the second water soluble polymer ispolyvinyl alcohol. The polyethylene oxide may have an average molecularweight greater than about 100,000, or about 200,000, or about 300,000,or about 600,000 and or less than about 10,000,000, or about 4,000,000,or about 1,500,000, or about 900,000. The tooth whitening compositionmay comprise greater than about 10%, or about 20%, or about 30% or about40% and/or less than about 90%, or about 60%, or about 50% by weight ofpolyethylene oxide. The tooth whitening composition may comprisemixtures of polyethylene oxides have different average molecularweights. The tooth whitening composition may comprise greater than about0.5%, or about 2%, or about 5% and/or less than about less than about90% or about 50%, or about 20%, or about 15% or about 10% by weight ofpolyvinyl alcohol. The ratio of the first water soluble polymer to thesecond water soluble polymer is between about 10:90 and about 90:0.5 orbetween about 50:2 and about 30:20. The polyvinyl alcohol may havevarying degrees of hydrolysis. The degree of hydrolysis signifies theextent of conversion of polyvinyl acetate to polyvinyl alcohol. Amixture of polyethylene oxide and polyvinyl alcohol will be moreadhesive and less cohesive as the degree of hydrolysis of the polyvinylalcohol increases. Thus, for the same amount of polyethylene oxide, lesspolyvinyl alcohol is required as the degree of hydrolysis of thepolyvinyl alcohol increases in order to provide the same level ofadhesiveness. The polyvinyl alcohol may be super hydrolyzed, fullyhydrolyzed, intermediately hydrolyzed, or partially hydrolyzed.Typically, the range of hydrolysis, from partially hydrolyzed to superhydrolyzed, is between about 70% (partially hydrolyzed) and about 99.5%(super hydrolyzed). In one embodiment, the range of hydrolysis isgreater than about 70%, or about 80%, or about 87% and/or less thanabout 99%, or about 95%, or about 91%. As used herein, the phrase“hydrolysis” is intended to refer to the level of hydrolysis of the rawmaterial before manufacture of the tooth whitening composition. Inanother embodiment, the range of hydrolysis is between about 87% andabout 91% and the amount of polyvinyl alcohol between about _5_% andabout _50_% by weight of the tooth whitening composition. The toothwhitening composition may also optionally include a plasticizer. In oneembodiment, the tooth whitening composition may comprise greater thanabout 1%, or about 10%, or about 20% and/or less than about 80%, orabout 60%, or about 80% by weight of a plasticizer. A preferredplasticizer is polyethylene glycol. A more preferred plasticizer is apolyethylene glycol having a molecular weight between about 200 andabout 9,000. The tooth whitening composition may also optionally includewater at the same levels as previously discussed herein. The toothwhitening composition. The tooth whitening composition may includehydrogen peroxide greater than about 0.5%, or about 3%, or about 6%and/or less than about 40%, or about 20%, or about 10% by weight of thetooth whitening composition. The foregoing embodiments of a toothwhitening composition comprising two water soluble polymers may alsoincorporate aspects of any of the other embodiments described herein,such as a mesh or scrim, water insoluble organic or inorganic additives,perforations, etc.

Non-limiting examples of the foregoing embodiments incorporating amixture of polyethylene oxide and polyvinyl alcohol are set forth below.It will be appreciated that these compositions may include additionalingredients or other ingredients may be substituted for those listed.Each example sets forth the tooth whitening composition formulationbefore drying and after drying.

EXAMPLE 1

Polyethylene Polyvinyl oxide alcohol WSR-1105 Gohsenol (MW GL-05SHydrogen 900,000) (86.5%-89%) PEG 600 Water peroxide % wt before 6 2 6.582.5 3 drying % wt after 30 10 35 10 15 drying

EXAMPLE 2

Polyethylene Polyvinyl oxide alcohol WSR-205 Gohsenol (MW NH-26 Hydrogen600,000) (99.4%) PEG 600 Water peroxide % wt before 7.5 0.5 5 85 2drying % wt after 40 2.5 25 22.5 10 drying

EXAMPLE 3

Polyethylene Polyvinyl oxide alcohol WRS-1105 Gohsenol (MW KH-17Hydrogen 900,000) (78.5-81.5%) PEG 600 Water peroxide % wt before 4 5 684 1 drying % wt after 20 25 30 19 6 drying

EXAMPLE 4

Polyethylene Polyvinyl oxide alcohol WSR-N750 Gohsenol (MW GL-05SHydrogen 300,000) (86.5-89%) PEG 600 Water peroxide % wt before 6.5 3 681.5 3 drying % wt after 34 15 30 6 15 drying

Embodiments of the polyethylene oxide/polyvinyl alcohol mixtures of thepresent invention, including examples 1 to 4, can be made by preparing afirst mixture comprising polyethylene oxide and a solvent, such aswater, and a second mixture comprising polyvinyl alcohol and a solvent,such as water. It will be appreciated that a mixture of solvents mightalso be used herein. Both mixtures are separately stirred until both thepolyethylene oxide and the polyvinyl alcohol are fully hydrated. Thefirst and second mixtures are combined and a tooth whitening agent(e.g., hydrogen peroxide) and optionally a plasticizer (e.g., PEG 600)are added. This tooth whitening composition may be cast on a backinglayer or a suitable drying surface. The tooth whitening composition isthen dried until a desired amount of the solvent has been removed. Thetooth whitening composition can be freeze dried or a drying tunnelincorporating radiant or convective heating can be used. In oneembodiment, the tooth whitening composition can be dried in drying boxusing a nitrogen air mixture at room temperature at a flow rate betweenabout 0.085 m³/min and about 0.3 m³/min. The drying time may be betweenabout 15 minutes and about 2 hours or between about 20 minutes and about60 minutes.

The above described embodiments of the present invention can be furthercombined with other layers such as a thin protective coating layer,e.g., of 10 nanometers (nm) to 500 microns (um) thickness or a backinglayer formed from a strip of material. The coating material is appliedin a sufficiently thin layer so as not to interfere with the flexibilityof the film and to allow the whitening strip to conform to anarrangement of a row of teeth. The coating materials can be one or acombination of high molecular weight (that is, molecular weights greaterthan 1,000,000 Dalton) and include, ethyl cellulose, propyl cellulose,isopropyl cellulose, butyl cellulose, t-butyl cellulose, celluloseacetate, and derivatives of polyvinyl alcohol such as polyvinyl acetateand shellac.

The tooth whitening products of the present invention can be packaged inpouches as individual strips or a roll of film can be provided in atape-like dispenser, wherein individuals strips can be cut from the rollfor use in the oral cavity or the film can be provided with perforationsor other frangible features to permit separation of predetermined lengthstrips from the roll of film. Optionally, the tooth whitening productsof the present invention can further include a release liner. Therelease liner can be formed from any material that exhibits lessaffinity for the film and/or web than the film or web exhibits foritself. The release liner can be formed from polymer films, paper,foils, woven, non-wovens, and other suitable materials known in the art.Optionally, the release liner can include a coating such as wax,silicone, Teflon®, fluoropolymers, etc. The films of the presentinvention can be formed directly on the release liner. The release linercan be cut to the desired size either before or after formation of thefilm thereupon. The tooth whitening products of the present inventioncan also be provided as liner for dental trays, such as those describedin U.S. Pat. No. 5,098,303, wherein the strips are incorporated into thetrough of the dental tray.

To use the tooth whitening products of the present invention, the filmwhen applied to the teeth surface when hydrated by saliva in the oralcavity or prewetted by dipping the strip in water will adhere to theteeth in an appropriate manner. In this regard, the tooth whiteningproduct is formed to have a width dimension suitable to cover a row ofteeth (upper or lower). Therefore, the tooth whitening product may beapplied to the upper set of teeth, or to the lower set of teeth eitherseparately or simultaneously. The length dimension of the toothwhitening product is determined by the amount of coverage desired. Inthis regard, the number of teeth which it is desired to whiten willdetermine the dimensions of the product. For instance, it may be desiredto only whiten the front teeth, which are most easily seen by others.Accordingly, the length of tooth whitening product can be reduced inthis case, as compared to the case where it is desired to whiten all ofthe teeth. The duration of application of product to the teeth willdepend upon the type and concentration of the tooth whitening agent, aswell as the type and intensity of extrinsic or intrinsic stain.

The embodiments described herein were chosen and described to providethe best illustration of the principles of the invention and itspractical application to thereby enable one of ordinary skill in the artto utilize the invention in various embodiments and with variousmodifications as are suited to the particular use contemplated. All suchmodifications and variations are within the scope of the invention asdetermined by the appended claims when interpreted in accordance withthe breadth to which they are fairly, legally and equitably entitled.

The dimensions and values disclosed herein are not to be understood asbeing strictly limited to the exact numerical values recited. Instead,unless otherwise specified, each such dimension is intended to mean boththe recited value and a functionally equivalent range surrounding thatvalue. For example, a dimension disclosed as “40 mm” is intended to mean“about 40 mm.”

Every document cited herein, including any cross referenced or relatedpatent or application and any patent application or patent to which thisapplication claims priority or benefit thereof, is hereby incorporatedherein by reference in its entirety unless expressly excluded orotherwise limited. The citation of any document is not an admission thatit is prior art with respect to any invention disclosed or claimedherein or that it alone, or in any combination with any other referenceor references, teaches, suggests or discloses any such invention.Further, to the extent that any meaning or definition of a term in thisdocument conflicts with any meaning or definition of the same term in adocument incorporated by reference, the meaning or definition assignedto that term in this document shall govern.

While particular embodiments of the present invention have beenillustrated and described, it would be obvious to those skilled in theart that various other changes and modifications can be made withoutdeparting from the spirit and scope of the invention. It is thereforeintended to cover in the appended claims all such changes andmodifications that are within the scope of this invention.

What is claimed is:
 1. A tooth whitening product, comprising: a firstlayer comprising a tooth whitening composition comprising first andsecond polymers, water, and a tooth whitening agent, wherein said firstpolymer is polyethylene oxide with an average molecular weight of fromabout 300,000 to about 900,000 and said second polymer is polyvinylalcohol, wherein the first layer contacts at least one tooth; a secondlayer that does not comprise a tooth whitening agent.
 2. The toothwhitening product of claim 1, wherein the concentration of said firstpolymer is between about 10% and about 90% by weight of said toothwhitening composition.
 3. The tooth whitening product of claim 1,wherein the concentration of said second polymer is between about 0.5%and about 50% by weight of said tooth whitening composition.
 4. Thetooth whitening product of claim 1, wherein the concentration of saidwater is between about 2% and about 90% by weight of said toothwhitening composition.
 5. The tooth whitening product of claim 1,wherein said tooth whitening composition further comprises a plasticizerhaving a concentration between about 1% and about 80% by weight of saidtooth whitening composition.
 6. The tooth whitening product of claim 5,wherein said plasticizer is polyethylene glycol.
 7. The tooth whiteningproduct of claim 1, wherein said polyvinyl alcohol has a hydrolysisbetween about 70% and about 91%.
 8. The tooth whitening product of claim1, wherein the second layer is a laminate.
 9. The tooth whiteningproduct of claim 1, wherein said tooth whitening composition comprises amixture of two or more polyethylene oxides and wherein said polyethyleneoxides have different average molecular weights.
 10. The tooth whiteningproduct of claim 1, wherein said tooth whitening agent of the firstlayer is hydrogen peroxide.
 11. The tooth whitening product of claim 1,wherein said first and second polymers are water soluble.
 12. The toothwhitening product of claim 1, wherein the second layer comprises atleast about 20%, by weight of the second layer, of a water hydratablepolymer.
 13. The tooth whitening product of claim 12, wherein the waterhydratable polymer is polyethylene oxide with an average molecularweight of from about 300,000 to about 900,000.
 14. The tooth whiteningproduct of claim 13, wherein there is more polyethylene oxide in thesecond layer than in the first layer, by total weight of the toothwhitening product.
 15. The tooth whitening product of claim 1, whereinthe second layer comprises an oral care active other than the toothwhitening agent.